wk13 Tissue cyst forming coccidia

What type of life cycle do Toxoplasma, Neospora, and Sarcocystis have?

Indirect life cycles (two-host coccidia; tissue-cyst forming).

What stage of Sarcocystis is found in the feces of the definitive host?

Sporocyst (not oocyst).

Why can't coccidia oocysts be distinguished on fecal exam?

Overlapping size range.

What is Toxoplasma gondii known for globally?

Most successful parasite worldwide; infects all warm-blooded animals.

Who are the definitive hosts of Toxoplasma gondii?

Cats.

Is Toxoplasma gondii zoonotic?

Yes.

What is the approximate global human seroprevalence of Toxoplasma gondii?

~31%.

What is the seroprevalence of Toxoplasma gondii in the U.S.?

~35%.

What percentage of cats shed oocysts?

~1-6%.

What are the main transmission routes of Toxoplasma gondii?

Undercooked meat, contaminated water/soil, cat feces, congenital transmission.

What are the life cycle stages of Toxoplasma gondii?

Oocysts → Sporozoites → Tachyzoites → Tissue cysts (bradyzoites).

How long do cats shed oocysts?

1-2 weeks.

What clinical signs occur in cats (definitive host)?

Transient, self-limiting small bowel diarrhea.

Are previously infected cats a major infection source?

No, minor source.

What is typical disease presentation in intermediate hosts?

Subclinical/asymptomatic in immunocompetent individuals.

What happens in congenital toxoplasmosis in livestock?

Abortions, placentitis, systemic fetal infection.

What are diagnostic methods for Toxoplasma gondii?

Serology (IgG, IgM), PCR, IFA, ELISA, immunohistochemistry.

Why are fecal exams unreliable for diagnosing Toxoplasma?

Oocysts shed intermittently.

What drugs are used to treat Toxoplasma gondii?

Sulfadiazine + pyrimethamine.

What are the two species of Neospora?

Neospora caninum and Neospora hughesi.

Is Neospora zoonotic?

No.

What disease is Neospora caninum known for in cattle?

Reproductive failure and abortions.

What hosts are involved with Neospora caninum?

Canids (DH) and cattle/mammals (IH).

What is the major transmission route in cattle for Neospora?

Transplacental transmission.

When do abortions typically occur in infected cows?

5-6 months gestation.

What clinical signs are seen in young calves infected with Neospora?

Neurological signs, ataxia, unable to rise, birth defects.

What clinical signs are seen in dogs infected with Neospora?

Ascending hindlimb paralysis, muscle atrophy, rigid hyperextension.

What diagnostic methods are used for Neospora?

Histology, IFAT, ELISA, PCR (Nc-5 sequence).

What is the main prevention strategy for Neospora in cattle?

Prevent contact with dogs/canids and ingestion of placental tissue.

Is there an effective treatment or vaccine for cattle infected with Neospora?

No.

What drugs are used to treat Neospora in dogs?

Clindamycin or trimethoprim-sulfadiazine + pyrimethamine.

How many species of Sarcocystis exist?

~130-200 species.

Who can serve as definitive hosts for Sarcocystis?

Canids, raccoons, birds, reptiles, mammals (including humans).

Are Sarcocystis infections pathogenic in definitive hosts?

Usually non-pathogenic.

Where are tissue cysts found in intermediate hosts called?

Sarcocysts.

What stage is excreted in feces of definitive hosts for Sarcocystis?

Sporocysts.

What disease is caused by Sarcocystis neurona?

Equine protozoal myeloencephalitis (EPM).

Who is the definitive host of Sarcocystis neurona?

Opossum.

What is the role of horses in Sarcocystis neurona infection?

Dead-end host.

What are the 'Three A's' of EPM?

Ataxia, asymmetry, atrophy.

What are other clinical signs of EPM?

Head tilt, cranial nerve deficits, difficulty swallowing, behavioral changes.

How is EPM diagnosed?

Serology (IFAT/ELISA), serum + CSF comparison, postmortem CNS lesions.

What CSF titer ratio indicates CNS infection?

<1:100.

What is the gold standard treatment for EPM?

Ponazuril (Marquis) oral paste.